Maybe those in North Dakota count just what was taken off... but many beekeepers in areas with less honey production remove ALL the honey (and that's what they count). They then feed sugar water in the fall to get the bees over winter.
So, sometimes the figure you hear is the entire production amount. I hear pretty often that you make more money by removing all the honey (at $3 a pound), and replacing it with sugar (at 40 cents a pound).